8 A company decides that its employees should follow an exercise programme for 30 minutes each day, with the aim that they lose weight and increase productivity. The weights, in kg , of a random sample of 8 employees at the start of the programme and after following the programme for 6 weeks are shown in the table.
| Employee | \(A\) | \(B\) | \(C\) | \(D\) | \(E\) | \(F\) | \(G\) | \(H\) |
| Weight before \(( \mathrm { kg } )\) | 98.6 | 87.3 | 90.4 | 85.2 | 100.5 | 92.4 | 89.9 | 91.3 |
| Weight after \(( \mathrm { kg } )\) | 93.5 | 85.2 | 88.2 | 84.6 | 95.4 | 89.3 | 86.0 | 87.6 |
Assuming that loss in weight is normally distributed, find a 95\% confidence interval for the mean loss in weight of the company's employees.
Test at the \(5 \%\) significance level whether, after the exercise programme, there is a reduction of more than 2.5 kg in the population mean weight.